During semiconductor wafer processing, it is necessary to locate and align the flat edges of the wafers in the wafer cassette to enable automated equipment to process the wafers and provide the proper wafer alignment during processing. A flat finder apparatus is used to align as many as twenty-five semiconductor wafers in a cassette or wafer boat. Flat finders are needed in almost every step in the manufacturing process, which can be a many as 170 different steps.
Wafer flats are located by placing a number of wafers in a flat locator and rotating the wafers until all the flats are aligned. During the rolling and alignment process, particles of silicon or other material resulting from surface and edge polishing, and other processing steps adhere to the surface and edges of the wafers. These particles lead to device defects if they are not removed.